1. Field of the Invention
The present invention is directed to a telephone communication system used for handling information such as messages, typically voice mail messages, and, more particularly, is directed to a system that provides a tightly coupled distributed architecture that allows substantially increased efficiency of equipment utilization, increased subscriber capability, modular expansion capability and low access blockage for subscribers and nonsubscribers.
2. Description of the Related Art
Typical voice mail systems are designed for operation in conjunction with a private business exchange (PBX). The typical systems include one or more separate call processing computers dedicated to serving a predetermined set of PBX lines and subscribers. Each processor stores the subscriber information for the subscribers assigned to that processor. The processors store messages in a common storage accessed over dedicated storage buses. Each call processor acts independently and competes for access to the common storage. Because each call processor serves a predetermined set of lines, when a message originator, whether a subscriber or non-subscriber, calls a subscriber and wishes to leave a voice message, if the lines dedicated to the subscriber are busy or if the call processing computer is unavailable for any other reason, the message originator is not allowed to leave a message. A processor does not have access to the subscriber information stored in another processor, thereby preventing other processors from handling the call. In like manner, if a subscriber wants to obtain his messages and the limited number of lines to the subscriber's dedicated call processing computer are busy or the processor is unavailable, the subscriber cannot get his messages. A prior art system as described above is typified by the system described in U.S. Pat. No. 4,371,752.